Pathway DMX Pathfinder CR Manual - Manual (Page 15)

DMX Distribution System Page 15
Operation
Remember that end-of-line termination is necessary on all individual DMX
cable runs. Source lines are all permanently terminated by integral resistors
in each Input Module, and likewise the auxiliary (return) wire pair of each
outgoing station line is terminated in each Output Module. The transmit
(send) wire pair of each station line, however, must be manually terminated
at its final destination receiving device. Most DMX-controlled equipment
incorporates this feature; if not, a suitable terminating plug should be inserted
into the device's pass-thru connector. Ensure that only one terminator is
connected to any one DMX run, otherwise the repeater circuit may become
overloaded. While it is not generally good practice to leave unused output
cable runs unterminated, this is unnecessary as each repeater circuit
incorporates an isolation relay that is open whenever the output line is not
patched.
.3 Advanced Patch Methods
As
can be readily appreciated, the DMX Distribution System is sufficiently
flexible to permit almost any signal routing possibility without breaking the
basic electrical rules of RS-422A/485.
For example, it may be desired to physically loop a data signal from a
receiving device at one station to one or more additional receivers at other
stations, bypassing the crosspoint matrix and opto-repeater circuitry of the
DMXPathfinder. This can be done easily with an unused cable run to
another output station. One cable is used for the input signal to the receiving
device, and the "thru" connector on the receiving device is patched to the
other cable run to be returned to the distribution rack. From there it can be
connected via a short male-to-male patch cord to another station's output
jack and sent to the next receiving device, and so on. Remember that this
scenario involves manual as opposed to electronic patching, thus the station
lines used must not be included in the DMX-Q patch file. This ensures that
the station lines' isolation relays are left open. It is especially important to
keep these cable runs electrically isolated from the DMXPathfinder
electronics if the signals being routed use voltages other that 5VDC.
Another possible patch scenario is to use a station line to input a DMX
source signal, then to use a patch cord at the DMXPathfinder to reconnect
that signal to the auxiliary I/O connector of an unused line of an Input
Module. The source signal can then be patched electronically to other
station lines. Again, the station line used for the DMX source must be left